Rotor for a high-speed electrical machine

Abstract

A rotor for a high-speed electrical machine with gas bearings includes at least one rotor side radial bearing, a rotor side axial bearing, a rotor body including the at least one rotor side radial bearing, and a rotor end piece including the rotor side axial bearing. When seen along the rotor's axis of rotation, a radial bearing section is defined as a section along which a radial bearing extends. Therein, the rotor end piece radially surrounds the rotor body at the interface of these two parts.

1 . A rotor for a high-speed electrical machine with gas bearings, the rotor comprising:
 at least one rotor side radial bearing,   a rotor side axial bearing,   a rotor body comprising the at least one rotor side radial bearing,   a rotor end piece comprising the rotor side axial bearing,   wherein, when seen along the rotor's axis of rotation, a radial bearing section is defined as a section along which a radial bearing extends,   wherein the rotor end piece radially surrounds the rotor body at the interface of these two parts.   
     
     
         2 . The rotor of  claim 1 , wherein the rotor body and the rotor end piece are joined by a press-fit, in particular wherein the press fit is a conical fit. 
     
     
         3 . The rotor of  claim 1 , wherein the rotor end piece, seen along the rotor's axis of rotation, does not substantially overlap a radial bearing section of the rotor body,
 in particular wherein the overlap is less than 15% or less than 10% or less than 5% of the diameter of the rotor body in the radial bearing section, or wherein there is no overlap at all.   
     
     
         4 . The rotor of  claim 1 , wherein the rotor body material has a CTE lower than 7E-6 K{circumflex over ( )}−1, in particular lower than 5E-6 K{circumflex over ( )}−1 even more in particular lower than 4E-6 K{circumflex over ( )}−1, and the rotor end piece material is a metal, in particular a steel. 
     
     
         5 . The rotor of  claim 1 , wherein the rotor body material has a HK5 or Vickers hardness larger than 10 GPa, in particular larger than 15 GPa, even more in particular larger than 20 GPa. 
     
     
         6 . The rotor of  claim 2 , wherein a length of a press fit section in which the rotor body and the rotor end piece overlap, seen along the rotor's axis of rotation, is less than 50% of the diameter of the rotor body, in particular less than 40% of the diameter of the rotor body, in particular less than 30% of the diameter of the rotor body. 
     
     
         7 . The rotor  claim 1 , wherein when seen along the rotor's axis of rotation, an axial bearing section is a section comprising the rotor side axial bearing, and wherein a circumferential groove is arranged between the axial bearing section and a section in which the rotor end piece and rotor body overlap,
 wherein a radial depth of the circumferential groove is at least 30%, in particular at least 50%, in particular at least 70% of a radial thickness of an annular section of the rotor end piece where it radially surrounds the rotor body.   
     
     
         8 . The rotor of  claim 1 , wherein the rotor end piece comprises a hollow section, the hollow section extending in the axial direction along at least the axial bearing section and in particular along at least 50% or 70% of the length of the rotor end piece in the axial direction, 
     
     
         9 . The rotor of  claim 8 , wherein the hollow section volume comprises or constitutes a ventilating duct establishing a fluid connection to a surrounding of the rotor, in particular wherein the ventilating duct is an axially extending through hole. 
     
     
         10 . The rotor  claim 8 , wherein the hollow section is enclosed in a gas-tight manner and in particular where the hollow section constitutes a press fit compensation volume arranged to receive gas displaced when joining the rotor body to the rotor end piece and thereby establishing the press fit, even more in particular wherein the press fit compensating volume has a volume of at least the one fifth of the volume of the part of the rotor body that is inserted into the rotor end piece. 
     
     
         11 . The rotor of  claim 1 , wherein the rotor is compressed in the axial direction by a tensioning bolt, in particular wherein at least the rotor end part and the rotor body are compressed, and optionally also a magnet section of the rotor, and optionally also an impeller or another load, is compressed by the tensioning bolt. 
     
     
         12 . The rotor of  claim 1 , wherein the rotor body is a solid body. 
     
     
         13 . The rotor of  claim 1 , wherein the rotor body is shaped to be a hollow cylinder. 
     
     
         14 . The rotor of  claim 1 , wherein the rotor comprises a permanent magnet, and when seen along the rotor's axis of rotation, a magnet section is a section along which the permanent magnet extends, and
 wherein
 either the permanent magnet is arranged inside the rotor body, in particular with the magnet section being at least approximately centred between two radial bearing sections, 
 or the permanent magnet is arranged at a distal end of the rotor body, opposite to the rotor end piece. 
   
     
     
         15 . The rotor of  claim 1 , wherein the rotor body, in a section inserted into the rotor end piece, has the same outer diameter as in an adjacent, proximal bearing section, and
 the same outer diameter as in a second, distal bearing section.   
     
     
         16 . The rotor of  claim 1 , wherein the rotor end piece comprises an axial bearing plate, the axial bearing plate being an annular plate and being seated on the rotor body, and
 wherein the material of the rotor body has a CTE lower than 7E-6 K{circumflex over ( )}−1, in particular lower than 5E-6 K{circumflex over ( )}−1 even more in particular lower than 4E-6 K{circumflex over ( )}− 1 , and the axial bearing plate is made of a metal, in particular of a steel.